Organic light-emitting display apparatus

ABSTRACT

An organic light-emitting display apparatus is provided. The apparatus includes an organic light-emitting diode emitting visible light, a driving thin film transistor driving the organic light-emitting diode, and a compensation thin film transistor. The compensation thin film transistor includes a compensation gate electrode, a compensation semiconductor layer, a compensation source electrode, and a compensation drain electrode. The compensation gate electrode includes a first gate electrode, and a second gate electrode electrically connected to the first gate electrode. The compensation drain electrode is electrically connected to the driving gate electrode of the driving thin film transistor. The compensation semiconductor layer includes a first semiconductor region overlapping the first gate electrode and a second semiconductor region overlapping the second gate electrode and disposed further from the compensation drain electrode than the first semiconductor region, and an area of the first semiconductor region is less than that of the second semiconductor region.

CLAIM OF PRIORITY

This application claims the benefit of Korean Patent Application No.10-2014-0122926, filed on Sep. 16, 2014, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One or more exemplary embodiments relate to an organic light-emittingdisplay apparatus.

2. Description of the Related Art

Organic light-emitting display apparatuses display images by usingorganic light-emitting diodes in which light is generated byrecombination of electrons and holes. Organic light-emitting displayapparatuses have advantages of fast response times and low electricpower consumption.

An organic light-emitting display apparatus (for example, an activematrix-type organic light-emitting display apparatus) generally includesa plurality of gate lines, a plurality of source lines, a plurality ofpower lines, and a plurality of pixels connected to the pluralities ofgate, source, and power lines and arranged in a matrix shape. In orderto drive each of the plurality of pixels, the pluralities of gate,source, and power lines transmit various signals to each of the pixels.

Meanwhile, for high resolution output, as each of the pixels becomessmaller, width of the lines connected to the pixels decreases anddistance between the lines decreases, and thus it becomes difficult todrive the plurality of pixels uniformly. Accordingly, the extent towhich picture quality of the organic light-emitting display apparatusmay be improved is limited.

SUMMARY OF THE INVENTION

One or more exemplary embodiments include an organic light-emittingdisplay apparatus having improved picture quality properties.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to one or more exemplary embodiments, an organiclight-emitting display apparatus includes an organic light-emittingdiode emitting visible light, a driving thin film transistor driving theorganic light-emitting diode and including a driving gate electrode, adriving semiconductor layer, a driving source electrode, and a drivingdrain electrode, and a compensation thin film transistor electricallyconnected to the driving thin film transistor and compensating forthreshold voltage of the driving thin film transistor. The compensationthin film transistor includes a compensation gate electrode, acompensation semiconductor layer, a compensation source electrode, and acompensation drain electrode. The compensation gate electrode includes afirst gate electrode, and a second gate electrode electrically connectedto the first gate electrode. The compensation drain electrode iselectrically connected to the driving gate electrode of the driving thinfilm transistor. The compensation semiconductor layer includes a firstsemiconductor region overlapping the first gate electrode and a secondsemiconductor region overlapping the second gate electrode and disposedfurther from the compensation drain electrode than the firstsemiconductor region, and an area of the first semiconductor region isless than that of the second semiconductor region.

A length of the first semiconductor region in a direction from thecompensation source electrode to the compensation drain electrode may beless than a length of the second semiconductor region in a directionfrom the compensation source electrode to the compensation drainelectrode.

A width of the first semiconductor region in a direction perpendicularto a direction of the compensation source electrode toward thecompensation drain electrode may be less than a width of the secondsemiconductor region in a direction perpendicular to a direction of thecompensation source electrode toward the compensation drain electrode.

The first gate electrode of the compensation gate electrode maycorrespond to a region of a wire, and the second gate electrode mayprotrude from the wire.

An area of the first gate electrode that overlaps the firstsemiconductor region and corresponds to a length in a direction from thecompensation source electrode to the compensation drain electrode mayhave a smaller width than an area of the second gate electrode thatoverlaps the second semiconductor region and corresponds to a length ina direction from the compensation source electrode to the compensationdrain electrode.

A wire to which the first gate electrode of the compensation gateelectrode corresponds may be a scanning line via which a scan signal fordriving the organic light-emitting diode is applied.

The apparatus may further include a switching thin film transistorconnected to the scanning line and including a switching gate electrode,a switching semiconductor layer, a switching source electrode, and aswitching drain electrode.

The compensation semiconductor layer may be curved such that the firstsemiconductor region and the second semiconductor region may not bedisposed side by side.

The apparatus may further include a first conductive member electricallyconnecting the driving gate electrode and the compensation drainelectrode, wherein the first conductive member may extend so as to bedisposed in a first contact hole which corresponds to the driving gateelectrode and in a second contact hole which corresponds to thecompensation drain electrode.

The apparatus may further include a storage capacitor which includes afirst electrode electrically connected to the compensation drainelectrode and a second electrode connected to a driving voltage line.

The first electrode of the storage capacitor may be connected to thedriving gate electrode.

The second electrode may include an opening formed in a region where thesecond electrode at least overlaps the first electrode.

The second electrode may be at least commonly included in at least twoadjacent pixels selected from among the pixels.

The driving voltage line may be connected to the second electrode.

The compensation source electrode may be electrically connected to thedriving drain electrode.

The apparatus may further include an emission control thin filmtransistor operating according to an emission control signal transmittedthrough an emission control line, wherein the compensation sourceelectrode may be electrically connected to a pixel electrode of theorganic light-emitting diode via the emission control thin filmtransistor.

The apparatus may further include an emission control thin filmtransistor operating according to an emission control signal transmittedthrough an emission control line, wherein the driving source electrodemay be electrically connected to a driving voltage line via the emissioncontrol thin film transistor.

The compensation source electrode and the compensation drain electrodemay be formed by doping the compensation semiconductor layer withimpurities.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 is a schematic block diagram of an organic light-emitting displayapparatus according to an embodiment;

FIG. 2 is an equivalent circuit diagram of one pixel of the organiclight-emitting display apparatus according to the present embodiment;

FIG. 3 is a schematic plan view of pixels of the organic light-emittingdisplay apparatus according to the present embodiment;

FIG. 4 is an enlarged view of K of FIG. 3;

FIG. 5 is a cross-sectional view taken along line V-V′ of FIG. 4; and

FIGS. 6 and 7 are graphs for describing a compensation thin filmtransistor included in the organic light-emitting display apparatusaccording to the present embodiment.

DETAILED DESCRIPTION OF THE INVENTION

As the inventive concept allows for various changes and numerousembodiments, exemplary embodiments will be illustrated in the drawingsand described in detail in the written description. The effect andfeature of the inventive concept and methods of accomplishing the samewill become apparent from the following description of the embodimentsin detail, taken in conjunction with the accompanying drawings. Thisinventive concept may, however, be embodied in many different forms andshould not be construed as limited to the exemplary embodiments setforth herein.

Expressions such as “at least one of,” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list.

While such terms as “first” and “second” may be used to describe variouscomponents, such components must not be limited to the above terms. Theabove terms are used only to distinguish one component from another.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It will be understood that the terms such as “include,” “comprise,” and“have” used herein specify the presence of stated features orcomponents, but do not preclude the presence or addition of one or moreother features or components.

It will be further understood that when a layer, region, or component isreferred to as being “formed on” another layer, region, or component, itcan be directly or indirectly formed on the other layer, region, orcomponent. That is, for example, intervening layers, regions, orcomponents may be present.

Sizes of components in the drawings may be exaggerated for convenienceof explanation. In other words, since sizes and thicknesses ofcomponents in the drawings are arbitrarily illustrated for convenienceof explanation, the following embodiments are not limited thereto.

In the following examples, the x-axis, the y-axis and the z-axis are notlimited to three axes of the rectangular coordinate system, and may beinterpreted in a broader sense. For example, the x-axis, the y-axis, andthe z-axis may be perpendicular to one another, or may representdifferent directions that are not perpendicular to one another.

When an embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order.

Hereinafter, the inventive concept will be described in detail withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. Like reference numerals in the drawingsdenote like elements, and thus repeated descriptions thereof will beomitted.

FIG. 1 is a schematic block diagram of an organic light-emitting displayapparatus 1000 according to an embodiment.

The organic light-emitting display apparatus 1000 according to thepresent embodiment may include a display 10 including a plurality ofpixels 1, a scan driving unit 20, a data driving unit 30, an emissioncontrol driving unit 40, and a controller 50.

In some embodiments, the emission control driving unit 40 may beomitted.

The display 10, disposed at the intersection of a plurality of scanninglines SL1 through SLn+1, a plurality of data lines DL1 through DLm and aplurality of emission control lines EL1 through ELn, includes theplurality of pixels 1 arranged substantially in a matrix shape. Theplurality of scanning lines SL1 through SLn+1 and the plurality ofemission control lines EL1 through ELn are extended in a seconddirection, which is a row direction of FIG. 1. The plurality of datalines DL1 through DLm and a driving voltage line ELVDDL are extended ina first direction, which is a column direction of FIG. 1. In one pixelline, n values of the plurality of scanning lines SL1 through SLn+1 maybe different from those of the plurality of emission control lines EL1through ELn.

As described above, if the emission control driving unit 40 is omitted,the plurality of emission control lines EL1 through ELn may be omitted.

Each of the pixels 1 may be connected to three of the plurality ofscanning lines SL1 through SLn+1 delivered to the display 10. In someembodiments, each of the pixels 1 may be connected to one or two of theplurality of scanning lines SL1 through SLn+1.

The scan driving unit 20 may generate and transmit three scan signals toeach of the pixels 1 through the plurality of scanning lines SL1 throughSLn+1. That is, the scan driving unit 20 sequentially supplies the scansignals to each of the pixels 1 through a first scanning line SL2through SLn, a second scanning line SL1 through SLn−1, or a thirdscanning line SL3 through SLn+1. An initialization voltage of thedisplay 10 may be applied to an initialization voltage line IL through apower supply source VINT.

Also, each of the pixels 1 may be connected to one of the plurality ofdata lines DL1 through DLm connected to the display 10 and one of theplurality of emission control lines EL1 through ELn connected to thedisplay 10.

The data driving unit 30 transmits a data signal to each of the pixels 1through the plurality of data lines DL1 through DLm. Whenever the scansignal is supplied to each of the pixels 1 through the first scanningline SL2 through SLn, the data signal is supplied to each of the pixels1 selected by the scan signal.

The emission control driving unit 40 generates and transmits an emissioncontrol signal to each of the pixels 1 through the plurality of emissioncontrol lines EL1 through ELn. The emission control signal controls alight-emitting time of the pixel 1. As described above, in someembodiments, the emission control driving unit 40 may be omitted.

The controller 50 converts a plurality of image signals R, G, and Btransmitted from the outside into a plurality of image data signals DR,DG, and DB, and transmits the plurality of image data signals DR, DG,and DB to the data driving unit 30. Also, as a vertical synchronizingsignal Vsync, a horizontal synchronizing signal Hsync and a clock signalMCLK are transmitted to the controller 50, the controller 50respectively generates and transmits control signals for controllingdrives of the scan driving unit 20, the data driving unit 30 and theemission control driving unit 40 to the scan driving unit 20, the datadriving unit 30 and the emission control driving unit 40. That is, thecontroller 50 respectively generates and transmits a scan drivingcontrol signal SCS for controlling the scan driving unit 20, a datadriving control signal DCS for controlling the data driving unit 30, andan emission driving control signal ECS for controlling the emissioncontrol driving unit 40 to the corresponding driving units 20, 30, and40.

A first power voltage ELVDD and a second power voltage ELVSS from theoutside are supplied to each of the pixels 1. The first power voltageELVDD may be a predetermined high-level voltage, and the second powervoltage ELVSS may be a voltage lower than the first power voltage ELVDDor a ground voltage. The first power voltage ELVDD is supplied to eachof the pixels 1 through the driving voltage line ELVDDL.

Each of the pixels 1 emits light of predetermined brightness by adriving current which is supplied to a light-emitting diode according tothe data signal transmitted through the plurality of data lines DL1through DLm.

FIG. 2 is an equivalent circuit diagram of one pixel 1 of the organiclight-emitting display apparatus 1000 according to the presentembodiment.

The pixel 1 of the organic light-emitting display apparatus 1000according to the present embodiment may include a pixel circuit 2including a plurality of thin film transistors T1 through T7 and atleast one storage capacitor Cst. The pixel 1 also includes an organiclight-emitting diode OLED emitting light by the driving current suppliedthrough the pixel circuit 2.

The plurality of thin film transistors T1 through T7 may include adriving thin film transistor T1, a switching thin film transistor T2, acompensation thin film transistor T3, a first initialization thin filmtransistor T4, a first emission control thin film transistor T5, asecond emission control thin film transistor T6, and a secondinitialization thin film transistor T7.

In some embodiments, at least one of the first initialization thin filmtransistor T4, the first emission control thin film transistor T5, thesecond emission control thin film transistor T6, and the secondinitialization thin film transistor T7 may be omitted among theplurality of thin film transistors T1 through T7.

The pixel 1 may include a first scanning line 14 transmitting a firstscan signal Sn to the switching thin film transistor T2 and thecompensation thin film transistor T3, a second scanning line 24transmitting a second scan signal Sn−1 to the first initialization thinfilm transistor T4, a third scanning line 34 transmitting a third scansignal Sn+1 to the second initialization thin film transistor T7, anemission control line 15 transmitting an emission control signal En tothe first emission control thin film transistor T5 and the secondemission control thin film transistor T6, a data line 16 transmitting adata signal Dm, a driving voltage line 26 transmitting the first powervoltage ELVDD, and an initialization voltage line 22 transmitting aninitialization voltage from power supply source VINT for initializingthe driving thin film transistor T1.

As described above, if at least one of the first initialization thinfilm transistor T4, the first emission control thin film transistor T5,the second emission control thin film transistor T6, and the secondinitialization thin film transistor T7 is omitted, at least one of thesecond scanning line 24, the third scanning line 34, and the emissioncontrol line 15 corresponding to the omitted thin film transistor may beomitted.

A driving gate electrode G1 of the driving thin film transistor T1 isconnected to a first electrode C1 of the storage capacitor Cst. Adriving source electrode S1 of the driving thin film transistor T1 maybe connected to the driving voltage line 26 via the first emissioncontrol thin film transistor T5. A driving drain electrode D1 of thedriving thin film transistor T1 is electrically connected to a pixelelectrode of the organic light-emitting diode OLED via the secondemission control thin film transistor T6. As the data signal Dm istransmitted to the driving thin film transistor T1 according toswitching operations of the switching thin film transistor T2, thedriving thin film transistor T1 supplies a driving current Id to theorganic light-emitting diode OLED.

A switching gate electrode G2 of the switching thin film transistor T2is connected to the first scanning line 14. A switching source electrodeS2 of the switching thin film transistor T2 is connected to the dataline 16. A switching drain electrode D2 of the switching thin filmtransistor T2 is connected to the driving source electrode S1 of thedriving thin film transistor T1 and is also connected to the drivingvoltage line 26 via the first emission control thin film transistor T5.As the switching thin film transistor T2 is turned on according to thefirst scan signal Sn transmitted through the first scanning line 14, theswitching thin film transistor T2 may perform the switching operation oftransmitting the data signal Dm transmitted through the data line 16 tothe driving source electrode S1 of the driving thin film transistor T1.

Compensation gate electrodes G31 and G32 of the compensation thin filmtransistor T3 are connected to the first scanning line 14. Acompensation source electrode S3 of the compensation thin filmtransistor T3 may be connected to the driving drain electrode D1 of thedriving thin film transistor T1.

In some embodiments, the compensation source electrode S3 of thecompensation thin film transistor T3 may be electrically connected tothe pixel electrode of the organic light-emitting diode OLED via thesecond emission control thin film transistor T6.

A compensation drain electrode D3 of the compensation thin filmtransistor T3 is electrically connected to the driving gate electrode G1of the driving thin film transistor T1.

Also, the compensation drain electrode D3 may be electrically connectedto the first electrode C1 of the storage capacitor Cst.

In some embodiments, the compensation drain electrode D3 may beelectrically connected to a first initialization source electrode S4 ofthe first initialization thin film transistor T4.

As the compensation thin film transistor T3 is turned on according tothe first scan signal Sn transmitted through the first scanning line 14,the compensation thin film transistor T3 may have the driving thin filmtransistor T1 diode-connected by connecting the driving gate electrodeG1 and the driving drain electrode D1 of the driving thin filmtransistor T1.

A first initialization gate electrode G4 of the first initializationthin film transistor T4 may be connected to the second scanning line 24.A first initialization drain electrode D4 of the first initializationthin film transistor T4 may be connected to the initialization voltageline 22. The first initialization source electrode S4 of the firstinitialization thin film transistor T4 may be connected to the firstelectrode C1 of the storage capacitor Cst, the compensation drainelectrode D3 of the compensation thin film transistor T3, and thedriving gate electrode G1 of the driving thin film transistor T1. As thefirst initialization thin film transistor T4 is turned on according tothe second scan signal Sn−1 transmitted through the second scanning line24, the first initialization thin film transistor T4 performs aninitialization operation of initializing the driving gate electrode G1of the driving thin film transistor T1 by transmitting theinitialization voltage to the driving gate electrode G1 of the drivingthin film transistor T1.

A first emission control gate electrode G5 of the first emission controlthin film transistor T5 may be connected to the emission control line15. A first emission control source electrode S5 of the first emissioncontrol thin film transistor T5 may be connected to the driving voltageline 26. A first emission control drain electrode D5 of the firstemission control thin film transistor T5 may be connected to the drivingsource electrode S1 of the driving thin film transistor T1 and theswitching drain electrode D2 of the switching thin film transistor T2.

A second emission control gate electrode G6 of the second emissioncontrol thin film transistor T6 may be connected to the emission controlline 15. A second emission control source electrode S6 of the secondemission control thin film transistor T6 may be connected to the drivingdrain electrode D1 of the driving thin film transistor T1 and thecompensation source electrode S3 of the compensation thin filmtransistor T3. A second emission control drain electrode D6 of thesecond emission control thin film transistor T6 may be electricallyconnected to the pixel electrode of the organic light-emitting diodeOLED. As the first emission control thin film transistor T5 and thesecond emission control thin film transistor T6 are simultaneouslyturned on according to the emission control signal En transmittedthrough the emission control line 15, the first power voltage ELVDD istransmitted to the organic light-emitting diode OLED so that the drivingcurrent Id flows in the organic light-emitting diode OLED.

A second initialization gate electrode G7 of the second initializationthin film transistor T7 may be connected to the third scanning line 34.A second initialization source electrode S7 of the second initializationthin film transistor T7 may be connected to the pixel electrode of theorganic light-emitting diode OLED. A second initialization drainelectrode D7 of the second initialization thin film transistor T7 may beconnected to the initialization voltage line 22. As the secondinitialization thin film transistor T7 is turned on according to thethird scan signal Sn+1 transmitted through the third scanning line 34,the second initialization thin film transistor T7 initializes the pixelelectrode of the organic light-emitting diode OLED.

A second electrode C2 of the storage capacitor Cst may be connected tothe driving voltage line 26. The first electrode C1 of the storagecapacitor Cst may be connected to the driving gate electrode G1 of thedriving thin film transistor T1, the compensation drain electrode D3 ofthe compensation thin film transistor T3, and the first initializationsource electrode S4 of the first initialization thin film transistor T4.

An opposite electrode of the organic light-emitting diode OLED may beconnected to the second power voltage ELVSS. As the driving current Idis supplied to the organic light-emitting diode OLED from the drivingthin film transistor T1, the organic light-emitting diode OLED displaysan image by emitting light.

FIG. 3 is a schematic plan view of the pixels 1 of the organiclight-emitting display apparatus 1000 according to the presentembodiment. Here, the two adjacent pixels 1 are illustrated forconvenience of explanation.

Referring to FIG. 3, the driving thin film transistor T1, the switchingthin film transistor T2, the compensation thin film transistor T3, thefirst initialization thin film transistor T4, the first emission controlthin film transistor T5, the second emission control thin filmtransistor T6, the second initialization thin film transistor T7, andthe storage capacitor Cst are formed in the pixel 1.

As described above, in some embodiments, at least one of the firstinitialization thin film transistor T4, the first emission control thinfilm transistor T5, the second emission control thin film transistor T6,and the second initialization thin film transistor T7 may be omitted.That is, all of the first initialization thin film transistor T4, thefirst emission control thin film transistor T5, the second emissioncontrol thin film transistor T6, and the second initialization thin filmtransistor T7 may be omitted.

For convenience of explanation, the organic light-emitting diode OLED isnot illustrated in FIG. 3.

The driving thin film transistor T1 includes a driving semiconductorlayer A1, the driving gate electrode G1, the driving source electrodeS1, and the driving drain electrode D1. The driving source electrode S1corresponds to a driving source region of the driving semiconductorlayer A1 which is doped with impurities, and the driving drain electrodeD1 corresponds to a driving drain region of the driving semiconductorlayer A1 which is doped with impurities. The driving gate electrode G1is connected to the first electrode C1 of the storage capacitor Cst, thecompensation drain electrode D3 of the compensation thin film transistorT3, and the first initialization source electrode S4 of the firstinitialization thin film transistor T4. In more detail, the driving gateelectrode G1 may be integrally formed on the same layer as the firstelectrode C1. The driving gate electrode G1 and the compensation drainelectrode D3 may be electrically connected via a first conductive memberCM1 provided in a first contact hole 51 and a second contact hole 52.That is, the first contact hole 51 is formed so as to correspond to thedriving gate electrode G1, and the second contact hole 52 is formed soas to correspond to the compensation drain electrode D3. The firstconductive member CM1 extends to be disposed in the first contact hole51 and the second contact hole 52. Thus, the first conductive member CM1comes into contact with the compensation drain electrode D3 at aposition corresponding to the second contact hole 52, and with thedriving gate electrode G1 at a position corresponding to the firstcontact hole 51.

Also, the driving gate electrode G1 and the first initialization sourceelectrode S4 are electrically connected by the first conductive memberCM1 disposed in the first contact hole 51 and the second contact hole52.

The switching thin film transistor T2 includes a switching semiconductorlayer A2, the switching gate electrode G2, the switching sourceelectrode S2, and the switching drain electrode D2. The switching sourceelectrode S2 corresponds to a switching source region of the switchingsemiconductor layer A2 which is doped with impurities, and the switchingdrain electrode D2 corresponds to a switching drain region of theswitching semiconductor layer A2 which is doped with impurities. Theswitching source electrode S2 is connected to the data line 16 via athird contact hole 53. The switching drain electrode D2 may be connectedto the driving thin film transistor T1 and the first emission controlthin film transistor T5. The switching gate electrode G2 is integrallyformed with the first scanning line 14.

The compensation thin film transistor T3 includes a compensationsemiconductor layer A3, the compensation gate electrode G3, thecompensation source electrode S3, and the compensation drain electrodeD3. The compensation source electrode S3 corresponds to a compensationsource region of the compensation semiconductor layer A3 which is dopedwith impurities, and the compensation drain electrode D3 corresponds toa compensation drain region of the compensation semiconductor layer A3which is doped with impurities.

The compensation gate electrode G3 has a dual gate electrode formed by aportion of the first scanning line 14 and a portion of the wireprotruding from the first scanning line 14, and thus prevents a leakagecurrent.

FIG. 4 is an enlarged view of K of FIG. 3. Referring to FIG. 4, thecompensation thin film transistor T3 has the dual gate electrodestructure, whereby the compensation gate electrode G3 includes the firstgate electrode G31 and the second gate electrode G32.

The first gate electrode G31, which is a region protruding from thefirst scanning line 14, is adjacent to the compensation drain electrodeD3.

The second gate electrode G32, which is a region of the first scanningline 14, is adjacent to the compensation source electrode S3.

The compensation semiconductor layer A3 includes a first semiconductorregion A31, at least a portion of which overlaps the first gateelectrode G31, and a second semiconductor region A32, at least a portionof which overlaps the second gate electrode G32.

The first semiconductor region A31 and the second semiconductor regionA32 may be a channel region of the compensation thin film transistor T3.The compensation thin film transistor T3 also includes a connectionportion DS, which is doped with impurities, disposed between firstsemiconductor region A31 and the second semiconductor region A32. Theconnection portion DS electrically connects the first semiconductorregion A31 and second semiconductor region A32 to each other.

In some embodiments, the first semiconductor region A31 and the secondsemiconductor region A32 are disposed not side by side to correspond tothe first gate electrode G31 and the second gate electrode G32,respectively, but in a curved form, which facilitates forming thecompensation thin film transistor T3 including the compensationsemiconductor layer A3 in a small region.

The first semiconductor region A31 has a width W31 and a length L31. Thewidth W31 and the length L31 are values corresponding to a size of thefirst semiconductor region A31 as a channel. That is, the length L31 isin a direction from the compensation source electrode S3 to thecompensation drain electrode D3 via the connection portion DS. The widthW31 is in a direction perpendicular to the length L31.

The second semiconductor region A32 has a width W32 and a length L32.The width W32 and the length L32 are values corresponding to a size ofthe second semiconductor region A32 as a channel. That is, the lengthL32 is in a direction from the compensation source electrode S3 to thecompensation drain electrode D3 via the connection portion DS. The widthW32 is in a direction perpendicular to the length L32.

An area of the first semiconductor region A31 is smaller than that ofthe second semiconductor region A32. That is, a product of the width W31and the length L31 of the first semiconductor region A31 is less thanthat of the width W32 and the length L32 of the second semiconductorregion A32.

In some embodiments, the width W31 of the first semiconductor region A31is less than the width W32 of the second semiconductor region A32. Also,a width of the first gate electrode G31 is less than that of the secondgate electrode G32.

In some embodiments, the length L31 of the first semiconductor regionA31 is shorter than the length L32 of the second semiconductor regionA32.

The compensation thin film transistor T3 transmits compensation voltageto the driving thin film transistor T1 so as to compensate for anoccurrence of a deviation in threshold voltage of the driving thin filmtransistor T1.

A parasitic capacitance between the driving gate electrode G1 and thedriving source electrode S1 of the driving thin film transistor T1, andthe like may cause a voltage shift, that is, kickback voltage. In thecase that the kickback voltage varies in different regions of theorganic light-emitting display apparatus 1000, deviations in an imagerepresented by the pixels 1 disposed in the different regions may occur.

According to the present embodiment, the first semiconductor region A31adjacent to the compensation drain electrode D3 of the compensation thinfilm transistor T3 electrically connected to the driving gate electrodeG1 of the driving thin film transistor T1 is formed smaller than thesecond semiconductor region A32. Thus, a deviation in kickback voltagein the driving thin film transistor T1 is reduced.

More details of this will be described with reference to FIGS. 6 and 7.

Turning back to FIG. 3, the first initialization thin film transistor T4includes a first initialization semiconductor layer A4, the firstinitialization gate electrode G4, the first initialization sourceelectrode S4, and the first initialization drain electrode D4. The firstinitialization source electrode S4 corresponds to a first initializationsource region of the first initialization semiconductor layer A4 whichis doped with impurities, and the first initialization drain electrodeD4 corresponds to a first initialization drain region of the firstinitialization semiconductor layer A4 which is doped with impurities.The first initialization drain electrode D4 may be connected to thesecond initialization thin film transistor T7, and the firstinitialization source electrode S4 may be connected to the driving gateelectrode G1 and the first electrode C1 of the storage capacitor Cst viathe first conductive member CM1 provided in the first contact hole 51and the second contact hole 52. The first initialization gate electrodeG4 is formed as a portion of the second scanning line 24. The firstinitialization semiconductor layer A4 may overlap the firstinitialization gate electrode G4 two times.

The first emission control thin film transistor T5 includes a firstemission control semiconductor layer A5, the first emission control gateelectrode G5, the first emission control source electrode S5, and thefirst emission control drain electrode D5. The first emission controlsource electrode S5 corresponds to a first emission control sourceregion of the first emission control semiconductor layer A5 which isdoped with impurities, and the first emission control drain electrode D5corresponds to a first emission control drain region of the firstemission control semiconductor layer A5 which is doped with impurities.The first emission control source electrode S5 may be connected to thedriving voltage line 26 via a fourth contact hole 54. The first emissioncontrol gate electrode G5 is formed as a portion of the emission controlline 15.

The second emission control thin film transistor T6 includes a secondemission control semiconductor layer A6, the second emission controlgate electrode G6, the second emission control source electrode S6, andthe second emission control drain electrode D6. The second emissioncontrol source electrode S6 corresponds to a second emission controlsource region of the second emission control semiconductor layer A6which is doped with impurities, and the second emission control drainelectrode D6 corresponds to a second emission control drain region ofthe second emission control semiconductor layer A6 which is doped withimpurities. The second emission control drain electrode D6 is connectedto the pixel electrode of the organic light-emitting diode OLED via asecond conductive member CM2 connected to a fifth contact hole 55 and avia hole VIA connected to the second conductive member CM2. The secondemission control gate electrode G6 is formed as a portion of theemission control line 15.

The second initialization thin film transistor T7 includes a secondinitialization semiconductor layer A7, the second initialization gateelectrode G7, the second initialization source electrode S7, and thesecond initialization drain electrode D7. The second initializationsource electrode S7 corresponds to a second initialization source regionof the second initialization semiconductor layer A7 which is doped withimpurities, and the second initialization drain electrode D7 correspondsto a second initialization drain region of the second initializationsemiconductor layer A7 which is doped with impurities. The secondinitialization source electrode S7 may be connected to theinitialization voltage line 22 via a sixth contact hole 56, and thesecond initialization drain electrode D7 is connected to the pixelelectrode of the organic light-emitting diode OLED via the secondconductive member CM2 connected to the fifth contact hole 55 and the viahole VIA connected to the second conductive member CM2. The secondinitialization gate electrode G7 is formed as a portion of the thirdscanning line 34.

The first electrode C1 of the storage capacitor Cst is directlyconnected to the driving gate electrode G1, and is connected to thefirst initialization thin film transistor T4 and the compensation thinfilm transistor T3 via the first conductive member CM1 provided in thefirst contact hole 51 and the second contact hole 52. The firstelectrode C1 may have a form of a floating electrode, and is disposed tooverlap the driving semiconductor layer A1.

While the second electrode C2 of the storage capacitor Cst overlaps thefirst electrode C1, the second electrode C2 does not completely coverthe first electrode C1. In some embodiments, the second electrode C2 mayinclude an opening OP exposing a portion of the first electrode C1, andthe first contact hole 51 is formed in the opening OP. The secondelectrodes C2 respectively included in the two adjacent pixels 1 may beconnected to each other. The driving voltage line 26 may be connected toa central portion of the second electrode C2 commonly included in thetwo adjacent pixels 1 via a seventh contact hole 57 to transmit thedriving voltage ELVDD simultaneously to the two pixels 1. That is, thedriving voltage ELVDD is applied to the two adjacent pixels 1 from onedriving voltage line 26 due to the second electrode C2 commonly includedin the two pixels 1.

In some embodiments, the first scanning line 14, the second scanningline 24, the third scanning line 34, and the emission control line 15may be all formed in the same layer and extend in the second direction.The first scanning line 14, the second scanning line 24, the thirdscanning line 34, and the emission control line 15 may be formed in thesame layer as the first electrode C1 of the storage capacitor Cst.

The data line 16, the driving voltage line 26, and the initializationvoltage line 22 may be all formed in the same layer and extend in thefirst direction.

In some embodiments, for example, the embodiment illustrate in FIG. 3,the two adjacent pixels 1 may share the driving voltage line 26. Thedriving voltage line 26 is disposed between the two adjacent pixels 1and extends in the first direction. The driving voltage line 26 isconnected to the first emission control thin film transistors T5respectively included in the two adjacent pixels 1 via the fourthcontact hole 54, and the second electrode C2 of the storage capacitorCst commonly included in the two adjacent pixels 1 via the seventhcontact hole 57. By sharing the driving voltage line 26, the twoadjacent pixels 1 may be symmetric with respect to the driving voltageline 26. Thus, the number of the driving voltage lines 26 may bedecreased, and design space may be easily secured as the number of wiresdecreases.

FIG. 5 is a cross-sectional view taken along line V-V′ of FIG. 4.

Referring to FIG. 5, the organic light-emitting display apparatus 1000may include a substrate 100.

A buffer layer 101 is formed on the substrate 100. The substrate 100 maybe formed of a glass material mainly including silicon dioxide (SiO₂).In some embodiments, the substrate 100 may be formed of a plasticmaterial. In other embodiments, the substrate 100 may be formed of ametal thin film.

The buffer layer 101, which prevents an impure element from penetratingthrough the substrate 100 and provides a planar surface to an upperportion of the substrate 100, may be formed of various materials whichmay serve the role. The buffer layer 101 is optional, and therefore maybe omitted.

The compensation semiconductor layer A3, the compensation sourceelectrode S3, and the compensation drain electrode D3 are disposed onthe buffer layer 101.

Although not illustrated, in some embodiments, the driving semiconductorlayer A1 of the driving thin film transistor T1 and the second emissioncontrol semiconductor layer A6 of the second emission control thin filmtransistor T6 may be formed on the buffer layer 101.

In some embodiments, the driving semiconductor layer A1 and the secondemission control semiconductor layer A6 may be formed of polysilicon,and may respectively include a channel region which is not doped withimpurities, and a source region and a drain region which are formed asimpurities are doped into both sides of the channel region. Here, theimpurities may vary with the type of a thin film transistor, and N-typeimpurities or P-type impurities may be used. Although not illustrated,the switching semiconductor layer A2 of the switching thin filmtransistor T2, the compensation semiconductor layer A3 of thecompensation thin film transistor T3, the first initializationsemiconductor layer A4 of the first initialization thin film transistorT4, the second initialization semiconductor layer A7 of the secondinitialization thin film transistor T7, the first emission controlsemiconductor layer A5 of the first emission control thin filmtransistor T5 may also be connected to the driving semiconductor layerA1 and the second emission control semiconductor layer A6 to be formedsimultaneously.

The compensation semiconductor layer A3 includes the first semiconductorregion A31 overlapping the first gate electrode G31, and the secondsemiconductor region A32 overlapping the second gate electrode G32.

In some embodiments, the length L31 of the first semiconductor regionA31 is less than the length L32 of the second semiconductor region A32.

The compensation source electrode S3 corresponds to a compensationsource region of the compensation semiconductor layer A3 which is dopedwith impurities, and is disposed adjacent to the second semiconductorregion A32.

The compensation drain electrode D3 corresponds to a compensation drainregion of the compensation semiconductor layer A3 which is doped withimpurities, and is disposed adjacent to the first semiconductor regionA31.

A first insulating layer 141 may be formed on the compensationsemiconductor layer A3, the compensation source electrode S3, and thecompensation drain electrode D3.

The compensation gate electrode G3 is formed on the first insulatinglayer 141. The compensation gate electrode G3 includes the first gateelectrode G31 and the second gate electrode G32.

As described above, the first gate electrode G31 overlaps the firstsemiconductor region A31, and the second gate electrode G32 overlaps thesecond semiconductor region A32.

Although not illustrated, in some embodiments, the driving gateelectrode G1, the switching gate electrode G2, the first scanning line14, the second scanning line 24, the third scanning line 34, and theemission control line 15 may be disposed on the first insulating layer141.

Also, in some embodiments, the second emission control gate electrode G6of the second emission control thin film transistor T6 and the firstelectrode C1 of the storage capacitor Cst may be formed on the firstinsulating layer 141.

A second insulating layer 142 covers the first gate electrode G31 andthe second gate electrode G32.

Although not illustrated, in some embodiments, the second electrode C2of the storage capacitor Cst may be disposed on the second insulatinglayer 142.

In some embodiments, the second electrode C2 of the storage capacitorCst includes an opening OP exposing a portion of the first electrode C1.Via the first contact hole 51 formed in the opening OP, the firstelectrode C1 may be connected to the compensation thin film transistorT3 and the first initialization thin film transistor T4.

In some embodiments, the storage capacitor Cst overlaps the driving thinfilm transistor T1. In more detail, the driving gate electrode G1 andthe first electrode C1 are formed as one body, and thus the storagecapacitor Cst and the driving thin film transistor T1 may be disposed tooverlap, thereby securing enough storage capacity of the storagecapacitor Cst.

An interlayer insulating layer 160 may be formed on the secondinsulating layer 142. In some embodiments, the interlayer insulatinglayer 160 may be formed on the second electrode C2 of the storagecapacitor Cst and the initialization voltage line 22.

Although not illustrated, in some embodiments, the data line 16, thedriving voltage line 26, and the initialization voltage line 22 may bedisposed on the interlayer insulating layer 160.

The first conductive member CM1 is disposed on the interlayer insulatinglayer 160, and is connected to the compensation drain electrode D3 viathe second contact hole 52. As shown in FIG. 3, the first conductivemember CM1 is also connected to the driving gate electrode G1 of thedriving thin film transistor T1 via the first contact hole 51.

Although not illustrated, in some embodiments, a protection film (notshown) or a planarization film (not shown) may be disposed on the firstconductive member CM1, and a pixel electrode (not shown) of anorganic-light emitting diode may be formed on the protection film (notshown) or the planarization film (not shown). The pixel electrode (notshown) is connected to the second conductive member CM2 exposed throughthe via hole VIA (Refer to FIG. 3), and the second conductive member CM2is connected to the second emission control drain electrode D6 via thefifth contact hole 55. Thus, the pixel electrode (not shown) may beelectrically connected to the second emission control drain electrodeD6.

The other members will also be described in detail.

The data line 16 is connected to the switching source electrode S2 viathe third contact hole 53. The first conductive member CM1 is connectedto the first initialization source electrode S4 via the second contacthole 52.

The switching source electrode S2 and the first initialization sourceelectrode S4 may be formed by respectively doping the switchingsemiconductor layer A2 and the first initialization semiconductor layerA4 with impurities.

The first initialization drain electrode D4 separated from the data line16 may be disposed on the substrate 100.

Meanwhile, the organic light-emitting diode includes a pixel electrode,an intermediate layer, and an opposite electrode. The intermediate layeris disposed between the pixel electrode and the opposite electrode, andincludes at least an emission layer so as to generate visible light. Theemission layer may be formed by an organic material.

In some embodiments, the intermediate layer may include at least oneselected from a hole injection layer, a hole transport layer, anelectron transport layer, and an electron injection layer, along withthe emission layer.

The pixel electrode may be an anode, and the opposite electrode may be acathode. In the other way, the pixel electrode may be a cathode, and theopposite electrode may be an anode.

Meanwhile, the source electrodes and the drain electrodes of theabove-described thin film transistors may be formed as the same layersas the corresponding semiconductor layers, respectively. That is, thesource electrode and the drain electrode of each of the thin filmtransistors may be formed of polysilicon selectively doped with a dopingmaterial.

However, the present embodiment is not limited thereto. The sourceelectrodes and the drain electrodes of the above-described thin filmtransistors may be formed as different layers from the correspondingsemiconductor layers, respectively, and the source electrodes and thedrain electrodes may be respectively connected to source regions anddrain regions of the corresponding semiconductor layers via contactholes.

FIGS. 6 and 7 are graphs for describing the compensation thin filmtransistor T3 included in the organic light-emitting display apparatus1000 according to the present embodiment.

FIG. 6 shows scattering of current by regions of the organiclight-emitting display apparatus 1000 according to changes in the lengthL31 and the width W31 of the first semiconductor region A31 of theabove-described compensation thin film transistor T3.

An x-axis of FIG. 6 denotes the length L31 of the first semiconductorregion A31, that is, a region of the compensation semiconductor layer A3which overlaps the first gate electrode G31 of the compensation gateelectrode G3, and a y-axis of FIG. 6 denotes the scattering of current.

Referring to FIG. 6, four curves respectively corresponding to the casesthat the width W31 of the first semiconductor region A31 is 1.8 μm, 2.8μm, 3.8 μm, and 4.8 μm are illustrated.

The scattering of current decreases as the width W31 of the firstsemiconductor region A31 decreases. That is, the scattering of currentis the least when the width W31 of the first semiconductor region A31 is1.8 μm.

Also, regarding all of the four curves shown in FIG. 6, as the lengthL31 of the first semiconductor region A31 decreases, the scattering ofcurrent decreases.

That is, the scattering of current decreases as the width W31 and thelength L31 of the first semiconductor region A31 of the compensationthin film transistor T3 decrease.

FIG. 7 shows scattering of current by regions of the organiclight-emitting display apparatus 1000 according to changes in the lengthL32 and the width W32 of the second semiconductor region A32 of theabove-described compensation thin film transistor T3.

An x-axis of FIG. 7 denotes the length L32 of the second semiconductorregion A32, that is, a region of the compensation semiconductor layer A3which overlaps the second gate electrode G32 of the compensation gateelectrode G3, and a y-axis of FIG. 7 denotes the scattering of current.

Referring to FIG. 7, four curves respectively corresponding to the casesthat the width W32 of the second semiconductor region A32 is 1.8 μm, 2.8μm, 3.8 μm, and 4.8 μm are illustrated.

The scattering of current decreases as the width W32 of the secondsemiconductor region A32 decreases. That is, the scattering of currentis the least when the width W32 of the second semiconductor region A32is 1.8 μm. However, a change in the scattering of current according tothe change in the width W32 of the second semiconductor region A32 isnot as great as that in the scattering of current according to thechange in the width W31 of the first semiconductor region A31.

Also, regarding all of the four curves shown in FIG. 7, as the lengthL32 of the second semiconductor region A32 increases, the scattering ofcurrent decreases.

That is, the scattering of current decreases as the length L32 of thesecond semiconductor region A32 of the compensation thin film transistorT3 increases. Also, as the width W32 of the second semiconductor regionA32 decreases, the scattering of current decreases while the amount ofdecrease is relatively little compared to the first semiconductor regionA31.

According to the present embodiment, the width W31 and the length L31 ofthe first semiconductor region A31 of the compensation thin filmtransistor T3 may be short such that scattering of current may bereduced, and the length L32 of the second semiconductor region A32 maybe long such that the scattering of current may be reduced. Thescattering of current by pixels in the whole region of the organiclight-emitting display apparatus may be reduced, thereby configuringpixels having uniform image quality in different regions. In addition,errors such as spots may be easily reduced or removed.

That is, according to the present embodiment, an area of the firstsemiconductor region A31 of the compensation thin film transistor T3 maybe less than that of the second semiconductor region A32, therebyimproving image quality. If the area of the first semiconductor regionA31 of the compensation thin film transistor T3 is too small, electricaloperations of the compensation thin film transistor T3 may be abnormal.Therefore, the width W31 and the length L31 of the first semiconductorregion A31 may be short such that the area of the first semiconductorregion A31 may be less than the area of the second semiconductor regionA32 and at the same time, scattering of current may be reduced within arange preventing abnormal electrical operations of the compensation thinfilm transistor T3.

As described above, according to one or more of the above exemplaryembodiments, the organic light-emitting display apparatus may have imagequality easy to improve.

While one or more exemplary embodiments have been described withreference to the appended figures, these are just examples and it willbe understood by those of ordinary skill in the art that various changesin form and details may be made therein without departing from thespirit and scope of the inventive concept as defined by the followingclaims.

What is claimed is:
 1. An organic light-emitting display apparatus,comprising: an organic light-emitting diode emitting visible light; adriving thin film transistor driving the organic light-emitting diodeand comprising a driving gate electrode, a driving semiconductor layer,a driving source electrode, and a driving drain electrode; and acompensation thin film transistor electrically connected to the drivingthin film transistor and compensating for threshold voltage of thedriving thin film transistor, the compensation thin film transistorcomprising a compensation gate electrode, a compensation semiconductorlayer, a compensation source electrode, and a compensation drainelectrode, the compensation gate electrode comprising a first gateelectrode and a second gate electrode electrically connected to eachother, the compensation drain electrode electrically connected to thedriving gate electrode of the driving thin film transistor, and thecompensation semiconductor layer comprising a first semiconductor regionoverlapping the first gate electrode and a second semiconductor regionoverlapping the second gate electrode and disposed further from thecompensation drain electrode than the first semiconductor region, and anarea of the first semiconductor region being less than that of thesecond semiconductor region.
 2. The apparatus of claim 1, wherein alength of the first semiconductor region in a direction from thecompensation source electrode to the compensation drain electrode isless than a length of the second semiconductor region in a directionfrom the compensation source electrode to the compensation drainelectrode.
 3. The apparatus of claim 1, wherein a width of the firstsemiconductor region in a direction perpendicular to a direction of thecompensation source electrode toward the compensation drain electrode isless than a width of the second semiconductor region in a directionperpendicular to a direction of the compensation source electrode towardthe compensation drain electrode.
 4. The apparatus of claim 1, whereinthe first gate electrode of the compensation gate electrode correspondsto a region of a wire, and the second gate electrode protrudes from thewire.
 5. The apparatus of claim 1, wherein an area of the first gateelectrode that overlaps the first semiconductor region and correspondsto a length in a direction from the compensation source electrode to thecompensation drain electrode has a smaller width than an area of thesecond gate electrode that overlaps the second semiconductor region andcorresponds to a length in a direction from the compensation sourceelectrode to the compensation drain electrode.
 6. The apparatus of claim5, wherein a wire which the first gate electrode of the compensationgate electrode corresponds to is a scanning line via which a scan signalfor driving the organic light-emitting diode is applied.
 7. Theapparatus of claim 6, further comprising a switching thin filmtransistor connected to the scanning line and comprising a switchinggate electrode, a switching semiconductor layer, a switching sourceelectrode, and a switching drain electrode.
 8. The apparatus of claim 1,wherein the compensation semiconductor layer is curved such that thefirst semiconductor region and the second semiconductor region are notdisposed side by side.
 9. The apparatus of claim 1, further comprising afirst conductive member electrically connecting the driving gateelectrode and the compensation drain electrode, wherein the firstconductive member extends so as to be disposed in a first contact holewhich corresponds to the driving gate electrode and in a second contacthole which corresponds to the compensation drain electrode.
 10. Theapparatus of claim 1, further comprising a storage capacitor whichcomprises a first electrode electrically connected to the compensationdrain electrode and a second electrode connected to a driving voltageline.
 11. The apparatus of claim 10, wherein the first electrode of thestorage capacitor is connected to the driving gate electrode.
 12. Theapparatus of claim 10, wherein the second electrode comprises an openingformed in a region where the second electrode at least overlaps thefirst electrode.
 13. The apparatus of claim 10, wherein the secondelectrode is at least commonly comprised in at least two adjacent pixelsselected from among the pixels.
 14. The apparatus of claim 10, whereinthe driving voltage line is connected to the second electrode.
 15. Theapparatus of claim 1, wherein the compensation source electrode iselectrically connected to the driving drain electrode.
 16. The apparatusof claim 1, further comprising an emission control thin film transistoroperating according to an emission control signal transmitted through anemission control line, wherein the compensation source electrode iselectrically connected to a pixel electrode of the organiclight-emitting diode via the emission control thin film transistor. 17.The apparatus of claim 1, further comprising an emission control thinfilm transistor operating according to an emission control signaltransmitted through an emission control line, wherein the driving sourceelectrode is electrically connected to a driving voltage line via theemission control thin film transistor.
 18. The apparatus of claim 1,wherein the compensation source electrode and the compensation drainelectrode are formed by doping the compensation semiconductor layer withimpurities.